Generally, the term “power factor” indicates the ratio of active power to apparent power. That is, the power factor is the ratio of power used to actually perform work to input power. A power factor is used as an important control factor in a place in which power control is necessary or in which technology for preventing wasted power consumption is necessary.
Power factor control serves to raise the power factor of a load with the aim of achieving a desired power factor. In the power factor control method mainly used by power utilities, the power factor is raised by decreasing apparent power. Here, the apparent power involves reactive power. The higher the reactive power, the higher the apparent power, but the lower the reactive power, the lower the apparent power. Accordingly, the apparent power may be decreased by decreasing reactive power, whereby the power factor may be ameliorated.
Meanwhile, in a device for controlling power factors for a switching board, a motor control board, or multiple loads, power factor control is individually performed for each of various kinds of loads (i.e. transformers, motors, home appliances, lighting products, etc.), and a great number of condensers is used to individually control the power factors of the respective loads. Therefore, a conventional switching board is problematic in that a high installation cost is incurred due to the use of multiple condensers. Also, because power factor control must be performed differently for the respective loads, a separate power factor controller must be installed for each of the loads. This results in an increase in the number of components and complicates design related to power factor control.
A power factor may be categorized into a lagging power factor, in which the phase of current lags the phase of voltage, and a leading power factor, in which the phase of current leads the phase of voltage. In most systems including a switching board, a lagging power factor is used as a power factor for loads such as motors and transformers, and in order to augment the power factor, a condenser is installed. Condensers may be installed in the bus-bar of a switching board in a centralized arrangement, may be installed so as to be distributed among the center and loads, or may be installed to be distributed to the terminals of loads. When a power factor is a leading power factor, a reactor may be used to increase the power factor.